Method of making dental porcelain



Patented May 7, 1935 UNITED STATES? PATENT OFFICE mesne assignments, 'to American. Porcelain Company, Chicago, 111. 1

No Drawing. Application March 19,- 1932,

Serial No. 600,069

g V V v BC S- -10H) l invention relates in generalto porcelain powder. T Bycombining or binding a portion of and has more particular reference to dental the feldspar with the flux in this preliminary porcelain and the manufacture thereof. mixture, I succeed in fixing the silex, as well as Among theobiects of the invention are to prothe volatile constituents of the feldspar, in such 5 vide a novel and improved porcelain powder for proportions that scarcely any shrinkage occurs 5" ,5 example, by dentists in the preparation when the final powder is formed, as for example, or construction of full or partial dentures, crowns, a dental structure, and fused.

inlays, and other dental structures, characterized To the foregoing preliminary fusion mixture y; features of substantially the consistency I add a suitable coloring agent, such as uranium,

10 of a heavypaste or putty when wet,- whereby to oxide, titanium oxide, or any other metallic oxide 10 facilitate forming the porcelain in' or about, 8, having thedesired color-characteristics to obtain, mold in a continuous homogeneous block prior for example, the uranium yellow color or tint into fusion or vitrification; of substantial freedom stead of the dark, or green color which usually 19m inkage orcracking with the consequent results if the uranium oxide'isgadded at a sub-' loss of time andmaterials in the final fusion of S q ntsta V the dental structure due to cracking, the filling To ac mp sh t coloring; I p e r t i d of the cracks with powdered porcelain and rethe small pieces obtained from. the preliminary fusing of the'dental structure as was heretofore fusion step in a' ball mill, to an impalpably fine frequently the case; ofa' porcelain powder wh n powder whichmay be divided into two portions.

formed and fused, which will not be susceptible To one portion thereof I add about 6% by'wei 2 to substantial internalv stresses and strains, of, say, uranium oxide, and} bake the mixture rendering dental structures made therefrom until itis fused.""Thisp with theilllanium weak and friable as a result of undue shrinkage Oxide, s neXt ground to a powder Which is mixed at the final fusion of the structure; of a porcelain in equal propor n wi h the'nortion which was powder which may readily be formed into dental not admixed with the coloring compound, so that 25 structures that are fully as hard, tougher, and the coloring compoun w makes p ut stronger than known porcelain dental structures; y Weight of the mixture of a preliminary mixture wherein a portion of the A final mixture may now be made of this colmaterial imparting translucency to the final ored material y mixing it in a ball mill With product in the proper proportion with the mafeldspar and with kaolin (to impart plasticity to -30 terial, imparting strength whereby to obviate the material), fusing the m xture and grinding some of the numerous fusing steps heretofore t o p p it use in the manufacture of employed in making porcelain, and to make thi dentures or other dental structures. Ihave found preliminary mixture of such characteristics that that an excellent formula for the final mixture the coloring agent employed will have the m t comprises substantially the following proportions 35 beneficial results so that the final powder will by Weight! have the translucency, hardness, and color re- P r nt quired for the dental structure desired; and a novel method of so combining feldspar, silex, and ggi gflfi mlxture kaolin with a coloring agent to produce porcelain Kaolin n 2 40 powder having the above mentioned advantages and improved properties. If desired, dehydrated kaolin may be employed Other objects of the invention will be apparent in t e fi a miXtuIe, but the Porcelain powder from the following description. described above fuses only at relatively high tem- In order to accomplish the foregoing objects, peratures, for example 1'700 F. or above, and 45 I make a preliminary mixture of substantially therefore the kaolin may be dehydrated in the 224 parts by weight of feldspar, with substanfinal fusi n st p u t d d: tially 346 parts by weight of a flux containing It Will, of Course, be pa t t at t e fore in uncombined form about 11 parts by weight going formula is merely illustrative of the pres-- of soda or sodium carbonate, 191 parts by weight ent preferred embodiment of my invention, and 50 of borax, and substantially 144 parts by weight the steps in the process as outlined, as well as of silex or crystalized silica. This mixture is the formula, may be modified without departing then melted or fused and drawn or run while from the spirit or scope of the invention. For hot into cold Water to break it up into small example, equal portions by weight of the powder 5 pieces which are subsequently ground to a fine resulting from the final fusion and grinding, as

described above, may be mixed with the powder after the addition of the kaolin and feldspar, but before the final fusion, and this mixture is fused to produce an excellent porcelain powder for dental purposes.

The final powder after grinding, may be prepared for molding by mixing it with water to a paste. This paste is readily adapted for forming in or about a mold of any desired size and shape and may thereafter be fused to produce the desired dental structure. powder, I have observed a marked advantage over known powders. My powder has when wet the consistency of a thick paste or of putty, .as.distinguished from the sandlike or granular appearance of known porcelain powders. This feature facilitates the molding operation and renders the wet porcelain readily conformable to, for exam-..'

ple, denture molds. I, When porcelain powder is made as described above, it may readily be formed into strong and tough dentures without cracking or checking, and without requiring the filling of shrinkage. cracks with additional powder and re-fuslng or re-baking as was done with prior art porcelains. such a porcelain powder by virtue of its relative freedom from shrinkage, substantially avoids internal stresses and strains which have prior to this invention materially weakenedor rendered friable the known porcelain dentures.

While I have described a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the inven-- tion and I do not wish to be limited to the precise details of construction set forth but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what ,I claim as new and desire to secure by letters Patent of the United States,

1. A method of making dental porcelain which comprises fusing a preliminary mixture c n- In molding the wet taining feldspar withsillca, fusing the product from the first said fusion step with a coloring agent, and fusing the colored mixture with feldspar and kaolin.

2. A method of making dental porcelain which comprises fusing a preliminary mixture containing feldspar with silica, fusing the product from the first said fusion step with a coloring a ent, f in the colored mixture with feldspar and kaolin, and grinding the product of said fusion steps.

3. A method of making dental porcelain which comprises fusing a preliminary mixture containing feldspar and silica, bringing this mixture while hot intocontact with cold water to facilifusing the ground product with a coloring agent,

and fusing the colored mixture with feldspar and kaolin.

4. A method of making dental porcelain which comprises fusing a preliminary mixture containing feldspar and silica, suddenly cooling thefuscd mixture 'to break it up into small particles fused product of feldspar and silica, fusing the 30 mixture of saidfused products with kaolin and feldspar, and grinding the fused mixture to. a powder. H

6. A method of making dental porcelain which comprises fusing a preliminary mixture containing feldspar and silica, fusing some of the resuitin Product with a coloring agent to'produce a colored product, mixing with said colored product some of the product from the first said fusion step,. and fusing the mixture last described with o feldspar and kaolin.

FRED P. HQI'IFMANN.

with feldspar and 25 

